SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21035b405b3fa178650f7252a0123bf4cc0fdbb37ad798e0fa414561fbf12afd' 
  AND token = 'VhPlVzgzXrOa6wrTeBPDphFBw4rAmvxgFzAM8PiPCeU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}